/// <summary>
/// Reduce disk size re-arranging unused spaces. Can change password. If temporary disk was not provided, use MemoryStream temp disk
/// </summary>
public long Shrink(string password = null, IDiskService tempDisk = null)
{
var originalSize = _disk.FileLength;
// if temp disk are not passed, use memory stream disk
using (var temp = tempDisk ?? new StreamDiskService(new MemoryStream()))
using (_locker.Write())
using (var engine = new LiteEngine(temp, password))
{
// read all collection
foreach (var collectionName in this.GetCollectionNames())
{
// first create all user indexes (exclude _id index)
foreach (var index in this.GetIndexes(collectionName).Where(x => x.Field != "_id"))
{
engine.EnsureIndex(collectionName, index.Field, index.Unique);
}
// now copy documents
var docs = this.Find(collectionName, Query.All());
engine.InsertBulk(collectionName, docs);
// fix collection sequence number
var seq = _collections.Get(collectionName).Sequence;
engine.Transaction(collectionName, true, (col) =>
{
col.Sequence = seq;
engine._pager.SetDirty(col);
return(true);
});
}
// copy user version
engine.UserVersion = this.UserVersion;
// set current disk size to exact new disk usage
_disk.SetLength(temp.FileLength);
// read new header page to start copy
var header = BasePage.ReadPage(temp.ReadPage(0)) as HeaderPage;
// copy (as is) all pages from temp disk to original disk
for (uint i = 0; i <= header.LastPageID; i++)
{
// skip lock page
if (i == 1)
{
continue;
}
var page = temp.ReadPage(i);
_disk.WritePage(i, page);
}
// create/destroy crypto class
if (_crypto != null)
{
_crypto.Dispose();
}
_crypto = password == null ? null : new AesEncryption(password, header.Salt);
// initialize all services again (crypto can be changed)
this.InitializeServices();
// return how many bytes are reduced
return(originalSize - temp.FileLength);
}
}
